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Objective: To determine whether docosahexaenoic acid will slow the course of r etinal degeneration in subgroups of patients with retinitis pigmentosa who are r eceiving vitamin A. Design: Acohort of 208 patients with retinitis pigmentosa, a ged 18 to 55 years, were randomly assigned to 1200 mg of docosahexaenoic acid pl us 15000 IU/d of vitamin A given as retinyl palmitate (DHA +A group) or control fatty acid plus 15000 IU/d of vitamin A (control +A group) and followed up ove r 4 years. Seventy percent of the patients in each group were taking vitamin A, 15000 IU/d, prior to entry. We compared rates of decline in ocular function in t he DHA +A vs control +A groups among the subgroups defined by use or nonuse of vitamin A prior to entry. We also determined whether decline in ocular function was related to red blood cell phosphatidylethanolamine docosahexaenoic acid lev el, dietary ω-3 fatty acid intake, or duration of vitamin A use. Main outcome measures were Humphrey Field Analyzer visual field sensitivity, 30-Hz electrore tinogram amplitude, and visual acuity. Results: Among patients not taking vitami n A prior to entry, those in the DHA +A group had a slower decline in field sen sitivity and electroretinogram amplitude than those in the control +A group ove r the first 2 years (P=.01 and P=.03, respectively); these differences were not observed in years 3 and 4 of follow-up or among patients taking vitamin A prior to entry. In the entire cohort, red blood cell phosphatidylethanolamine docosah exaenoic acid level was inversely related to rate of decline in total field sens itivity over 4 years (test for trend, P=0.05). This was particularly evident ove r the first 2 years among those not on vitamin A prior to entry (test for trend, P=0.003). In the entire control +A group, dietary ω-3 fatty acid intake was inversely related to loss of total field sensitivity over 4 years (intake,< 0.20 vs ≥0.20 g/d; P= 0.02). The duration of vitamin A supplementation prior to ent ry was inversely related to rate of decline in electroretinogram amplitude (P=.0 08). Conclusions: For patients with retinitis pigmentosa beginning vitamin A the rapy, addition of docosahexaenoic acid, 1200 mg/d, slowed the course of disease for 2 years. Among patients on vitamin A for at least 2 years, a diet rich in ω -3 fatty acids (≥0.20 g/d) slowed the decline in visual field sensitivity.
Objective: To determine whether docosahexaenoic acid will slow the course of r etinal degeneration in subgroups of patients with retinitis pigmentosa who are r eceiving vitamin A. Design: Acohort of 208 patients with retinitis pigmentosa, a ged 18 to 55 years, were randomly assigned to 1200 mg of docosahexaenoic acid pl us 15000 IU / d of vitamin A given as retinyl palmitate (DHA + A group) or control fatty acid plus 15000 IU / d of vitamin A (control + A group) and followed up ove r 4 years. Seventy percent of the patients in each group were taking vitamin A, 15000 IU / d, prior to entry. We compared rates of decline in ocular function in t he DHA + A vs control + A groups among the subgroups defined by use or nonuse of vitamin A prior to entry. We also determined either decline in ocular function was related to red blood cell phosphatidylethanolamine docosahexaenoic acid lev el, dietary omega-3 fatty acid intake, or duration of vitamin A use. Main outcome measures were Humphrey Field Analyzer vi sual field sensitivity, 30-Hz electroretinogram amplitude, and visual acuity. Results: Among patients not taking vitami n A prior to entry, those in the DHA + A group had a slower decline in field sen sensitivity and electroretinogram amplitude than those in the control + A group ove r the first 2 years (P = .01 and P = .03, respectively); these differences were not observed in years 3 and 4 of follow-up or among patients taking vitamin A prior to entry. In the entire cohort, red blood cell phosphatidylethanolamine docosah exaenoic acid level was inversely related to rate of decline in total field sens itivity over 4 years (test for trend, P = 0.05). This was particularly evident ove r the first 2 years among those not on vitamin A prior to entry (test for trend, P = 0.003). In the entire control + A group, dietary omega-3 fatty acid intake was inversely related to loss of total field sensitivity over 4 years (intake, <0.20 vs ≥ 0.20 g / d; P = 0.02). The duration of vitamin A supplementation prior to e nt ry was inversely related to rate of decline in electroretinogram amplitude (P = .0 08). Conclusions: For patients with retinitis pigmentosa beginning vitamin A the rapy, addition of docosahexaenoic acid, 1200 mg / d, slowed the course of disease for 2 years . Amongpatients on vitamin A for at least 2 years, a diet rich in ω -3 fatty acids (≥0.20 g / d) slowed the decline in visual field sensitivity.